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A reassessment of Iteravis huchzermeyeri and Gansus zheni from the Jehol Biota in western Liaoning, China Shu-bin Ju, Xu-ri Wang, Yi-chuan Liu, Yang Wang

Citation: Shu-bin Ju, Xu-ri Wang, Yi-chuan Liu, Yang Wang, 2021. A reassessment ofIteravis huchzermeyeri and Gansus zheni from the Jehol Biota in western Liaoning, China, China Geology, 4, 197-204. doi: 10.31035/cg2020066.

View online: https://doi.org/10.31035/cg2020066

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A reassessment of Iteravis huchzermeyeri and Gansus zheni from the Jehol Biota in western Liaoning, China Shu-bin Jua, b, Xu-ri Wanga,*, Yi-chuan Liua, b, Yang Wanga a Institute of Geology, Chinese Academy of Geological Sciences, Key Laboratory of Stratigraphy and Paleontology of the Ministry of Natural Resources, Beijing 100037, China b China University of Geosciences (Beijing), Beijing 100083, China

A R T I C L E I N F O A B S T R A C T

Article history: The authors reassessed the taxonomic distinction of Iteravis huchzermeyeri and Gansus zheni, which are Received 2 September 2020 two species of Ornithuromorpha based on specimens from the same locality in western Liaoning and Received in revised form 9 November 2020 Accepted 13 November 2020 derive from the Jehol Biota. The detailed comparisons of the holotype and referred specimens of both Available online 24 November 2020 species, reveal no anatomical features that distinguish these taxa as separate species. Some minor

differences are considered to relate to ontogenetic or interspecific differences. The stratigraphic occurrence Keywords: for both specimens is the Lower Cretaceous Jiufotang Formation. Accordingly, the authors conclude that Jehol Biota Iteravis huchzermeyeri has priority, by 15 days, for this taxon and that Gansus zheni is a junior synonym. Lower Cretaceous Ornithuromorpha The diagnosis of Iteravis huchzermeyeri is revised based on further study on all specimens referred to this Synonym species. Its generic distinction from Gansus is maintained thereby removing a potential genus-level Geological survey engineering correlation linking Xiagou Formation in Gansu Province with the Jiufotang Formation in Liaoning Western Liaoning Province.

1. Introduction between the ilium and ischium. A large number of fossils of ornithuromorphs have been found in China preserved with not Ornithuromorpha is the most inclusive clade that includes only clear skeletal anatomical features, but also feathers, extant birds but not Mesozoic Enantiornithes (Chiappe LM, gastroliths and even skin impressions, which are significant 2002). As of July 2020, more than 20 species of for studying the origin, radiation and life habits of species in Ornithuromorpha have been reported from the Lower this clade (Zhou ZH and Zhang FC, 2001; You HL et al., Cretaceous in China, which are mostly distributed in the Jehol 2006; Chiappe LM et al., 2014; Zhou S et al., 2014; Wang M Biota in northern Hebei, western Liaoning and the et al., 2016; Zheng XT et al., 2018). neighboring areas of Inner Mongolia (Zhou ZH and Zhang Over the last 20 years, lots of new species of FC, 2001, 2005; Chiappe LM et al., 2014; Wang M et al., Ornithuromorpha have been coined based on specimens 2015). The characteristics that distinguish Ornithuromorpha uncovered from the Jehol Biota in China (e.g., Chaoyangia from other Mesozoic birds include the U-shaped furcula beishanensis, Yixianornis grabaui, Yanornis martini, Hongshanornis longicresta, Archaeorhynchus spathula, without hypocleideum, rectangular sternum with a keel, as Jianchangornis microdonta, Longicrusavis houi, Schizooura well as completely fused metatarsals. According to the lii, Piscivoravis lii, Iteravis huchzermeyeri, Gansus zheni, morphological characteristics, most species of this group have Tianyuornis cheni, Archaeornithura meemannae, strong flight abilities. Some species still retain primitive Changzuiornis ahgmi, Bellulia rectusunguis, Eogranivora features, such as the teeth, the pubic symphysis developed at edentulata, Khinganornis hulunbuirensis) (Hou LH and the distal end of the pubic bone, and no ilium ischial foramen Zhang J, 1993; Zhou ZH and Zhang FC, 2001, 2005, 2006; Zhou FC et al., 2009; O’Connor JK et al., 2010; Zhou S et al., First author: E-mail address: [email protected] (Shu-bin Ju). 2014; Liu D et al., 2014; 2018; Wang M et al., 2015, 2016; * Corresponding author: E-mail address: [email protected] (Xu-ri Wang). Huang JD et al., 2016; Wang XR et al., 2020). Because doi:10.31035/cg2020066 different researchers may study different specimens of the 2096-5192/© 2021 China Geology Editorial Office. same species more or less simultaneously, it is likely that 198 Ju et al. / China Geology 2 (2021) 197−204 synonyms of a single species could be published. Iteravis stratigraphic occurrence for I. huchzermeyeri should be the

huchzermeyeri (Zhou S et al. 2014) and Gansus zheni (Liu D Lower Cretaceous Jiufotang Formation. et al. 2014) were both uncovered at Sihedang town, Lingyuan City, Liaoning Province. The former was reported from the 3. Description and comparison Yixian Formation and the latter was from the Jiufotang Formation. I. huchzermeyeri was published 15 days earlier The central axial lengths from head to tail for the holotype than G. zheni. Most importantly, they have very similar specimens of I. huchzermeyeri (IVPP V18958) and G. zheni characteristics and very close phylogenetic relationship (Zhou (BMNHC-Ph1342), and the referred specimens of G. zheni S et al., 2014; Liu D et al., 2014). Wang X et al. (2018) (BMNHC-Ph1318) are about 204.3 mm, 195.7 mm and 217 mm, proposed that G. zheni was a synonym of I. huchzermeyeri, respectively, showing a variation in body length of less than but they did not conduct detailed comparisons and discussion. 10%. Although no osteohistological analyses have been taken G. zheni provided the best-known example of genus-level for the studied materials, the well ossified periosteal surfaces avian clade correlation between two broadly separated basins of the preserved elements and the complete fusion of the (being closely related to Gansus yumenensis found about tibiotarsus and tarsometatarsus indicated that they all were 2000 km distant in the Xiagou Formation, Gansu Province) adults or near-adults that had ceased to grow (Zhou S et al., and represented the most advanced bird for the Jehol Biota 2014; Liu D et al., 2014). (Liu D et al., 2014). It is worthy to clarify its validity, horizon Skulls of IVPP V18958, BMNHC-Ph1342 and BMNHC- Ph1318 are sub-triangular in shape, with a long rostrum and relationship with I. huchzermeyeri and G. yumenensis. nearly half of the skull length. The distinct pores are present 2. Systematic Paleontology on the lateral surface of premaxilla of IVPP V18958, which might represent vascularization of the horny beak. Similar Aves Linnaeus C, 1758 pores are also present on the lateral surface of the premaxilla Ornithothoraces Chiappe LM, 1995 and maxilla of BMNHC-Ph1342. The dentaries of IVPP Ornithuromorpha Chiappe LM, 2002 V18958, BMNHC-Ph1342 and BMNHC-Ph1318 are Iteravis huchzermeyeri Zhou S et al., 2014 relatively straight, and their posterior ends are slightly curved Revised diagnosis: Premaxillary corpus elongate and towards the ventral sides. The distal end of the surangular is toothless; maxilla and dentary with numerous small teeth; deeply concave in IVPP V18958, while this part is not visible rostrum 50% of skull length; ethmoid bone lining rostral half in BMNHC-Ph1318 (Fig. 1). The frontal is overlapped by the of the orbit; sternal margin of the coracoid extended nearly radius of IVPP V18958. There is a narrow salt gland fossa on equally medially and laterally; rostral margin of the sternum the frontal of BMNHC-Ph1342, which is smaller and strongly arched, defining an acute angle slightly less than 90°; narrower than that of Ichthyornis and Hesperornis (Wang X et alular metacarpal short and narrow, slightly more than half the al., 2018). The teeth are present on both dentary and maxilla width of the major metacarpal; pubic strongly curved dorsally of IVPP V18958, with several teeth mutually intercalating. from the distal 1/3 and with dorsally expanded distal boot; However, very small teeth are only visible on the dentary of ischium with concave ventral margin and prominent BMNHC-Ph342 and BMNHC-Ph1318. It is not certain triangular-shaped dorsal process at the midpoint. whether teeth are preserved on the premaxilla and maxilla. Holotype: A nearly complete individual preserved in a Teeth are often covered by other bones during fossilization single slab with feather impressions around the forelimbs and because there are many regularly dislocated bones with gastroliths in the abdominal area. It is housed at the Institute complex structure in the skull. This is especially so for the of Vertebrate Paleontology and Paleoanthropology, Chinese maxilla and dentary which often overlap to prevent observing Academy of Sciences, under the collection number of IVPP the teeth. For example, there were no visible teeth on the V18958. maxilla and dentary on the holotype of Hongshanornis Paratype: A nearly complete individual preserved in a longicresta (Zhou ZH and Zhang FC, 2005), while teeth were single slab with feather impressions around the forelimbs and later observed on the dentary of other referred specimens gastroliths in the abdominal area. It is housed at Beijing (Chiappe LM et al., 2014). There are no teeth on the Museum of Natural History, under the collection number of premaxilla of IVPP V18958. BMNHC-Ph1342. There are 13 cervical vertebrae in IVPP V18958, and 12- Referred materials: Two nearly complete individuals 13 in BMNHC-Ph1342. In IVPP V18958, the cranial cervical preserved in single slabs. They are housed at Beijing Museum vertebrae are more elongate than the caudal ones, with the of Natural History, under the collection numbers of BMNHC- length approximately twice of the width, while the caudal six Ph1318 and BMNHC-Ph1394. preserved vertebrae are much shorter, with nearly equal length Locality and horizon: All published specimens of I. and width (Zhou S et al., 2014). In BMNHC-Ph1318, the huchzermeyeri (including the junior synonyms listed here) sixth and seventh cervical vertebrae are extremely elongate, were uncoverd from Sihedang town near Lingyuan City, while the proximal and distal cervical vertebrae are relatively western Liaoning. Previously reported specimens are from the shorter. The difference might be related with preservation Yixian Formation or Jiufotang Formation. Actually, the conditions because the cervical vertebrae are too fragile to be Ju et al. / China Geology 2 (2021) 197−204 199 deformed during preservation. Cervical ribs are slightly the coracoid neck is significantly compressed mediolaterally. shorter than the corresponding cervical length and gradually The procoracoid process is prominently expanded and the tapered distally in IVPP V18958. Several cervical ribs are laterodistal process is gently hooked anteriorly (Fig. 2b) (Liu also preserved in BMNHC-Ph1318 with similar morphologies D et al., 2014). The sternal margin of the coracoid of as those of IVPP V18958. The absence of cervical ribs in BMNHC-Ph1342 extends nearly equally medially and BMNHC-Ph1342 is possibly due to preservation. The laterally, which is similar to that of IVPP V18958, but synsacrum of IVPP V18958 is mostly covered by other bones, different from that of G. yumenensis, in which it extends with only the proximal and distal surfaces exposed with flat much more laterally than medially (Fig. 2c). The U-shaped ventral surface. There is a broad groove on the ventral surface furcula of BMNHC-Ph1342 is slender and has an of the synsacrum of BMNHC-PH1318. Five to six free interclavicular angle of approximately 60°. This feature is one delicate caudal vertebrae are preserved in IVPP V18958, of these originally considered to distinguish G. zheni from G. which are relatively longer than the pygostyle. The pygostyle yumenensis (40°) (Liu D et al., 2014), while it is the same as of BMNHC-Ph1342 is formed by three to four fused caudal that of IVPP V18958 (60°). vertebrae. A thin ridge is developed in the proximal ventral The sternum of BMNHC-Ph1342 is craniocaudally margin, and a groove is present on the ventral surface, which elongate, nearly twice of its width, with a deep keel extending is very similar to that of IVPP V18958. through the middle section, and the rostral margin forming an The coracoids of IVPP V18958, BMNHC-Ph1342 and angle of less than 90° (Fig. 2b), which is the same as that of BMNHC-Ph1318 are similar in morphology, and are strut- IVPP V18958 (Fig. 2a) but different from that of G. shaped with the ratio of length to width of about 1.4. In IVPP yumenensis (140°) (Fig. 2d). The caudal margin of the V18958, the coracoid neck is strongly convex. The sternum of BMNHC-Ph1342 is covered by gastroliths and procoracoid process is relatively straight and the laterodistal other bones, which prevents establishing the exact process is hooked anteriorly (Fig. 2a). In BMNHC-Ph1342, morphology.

(a)

l eth

m prm

d t q sa hy 1 cm

(b) f

eth

prm

q t d hy sa 1 cm

Fig. 1. Photograph of the skull of Iteravis huchzermeyeri IVPP V18958 (a) (under normal light) and Gansus zheni BMNHC-Ph 1318 (b) (under UV lamp). prm–premaxilla; m–maxilla; d–dentary; t–teeth; hy–hyoid; l–lacrimal; eth–ethmoid; sa–surangular; q–quadrate; f–frontal. 200 Ju et al. / China Geology 2 (2021) 197−204

The humeri of IVPP V18958 and BMNHC-Ph1342 are yumenensis is relatively longer than the humerus similar in morphology. The left ulna of IVPP V18958 is (ulna/humerus=1.1) (Fig. 3c) (You HL et al., 2006). broken at the one third of length from the proximal end and The proximal ends of the major and minor metacarpals of partially overlapped by the left radius. The proximal end of IVPP V18958 are incompletely fused (Fig. 3a; Zhou S et al., the right ulna of IVPP V18958 is partially covered by the 2014). However, the components of the carpometacarpus of right tibia. It is difficult to determine the exact length and its BMNHC-Ph1342 are fully fused both proximally and distally characteristics. The ulna of BMNHC-Ph1342 is as long as the (Liu D et al., 2014). The alular metacarpal of BMNHC- humerus (ulna/humerus=1.03), and its proximal quarter is Ph1342 is relatively narrower than the major metacarpal (Fig. slightly curved cranially (Fig. 3b). The ulna of IVPP V18958 3b), which is similar with those of IVPP V18958 and G. is similar to that of BMNHC-Ph1342, with the mid-shaft yumenensis (Fig. 3d). width nearly twice the width of the radius. The ulna of G. The alular digit of both IVPP V18958 and BMNHC-

(a) (b) fu fu

co co lap sc 90° sc lap 90° k st

k st

140° co

Fig. 2. Photograph of the thoracic girdle and sternum of Iteravis huchzermeyeri IVPP V18958 (a) and Gansus zheni BMNHC-Ph 1342 (b); Photograph of the thoracic girdle of Gansus yumensensis (c); Photograph of the sternum of Gansus yumensensis (d). fu–furcula; co–coracoid; sc–scapula; st–sternum; k–keel; lap–laterodistal process; g–gastroliths. Ju et al. / China Geology 2 (2021) 197−204 201

Ph1342 are short, not distally surpassing the distal end of the BMNHC-Ph1342, but opposite to that of G. yumenensis major metacarpal. The alular phalanx is slightly curved, but a which the media condyle has similar width to the lateral bit larger than that of the major digit. The major digit is nearly condyle (Fig. 4c). as long as the carpometacarpus, with a strong first phalanx The components of the tarsometatarsus are completely three times wider than the second one (Figs. 3a, b). However, fused in IVPP V18958 and BMNHC-Ph1342 (Zhou S et al., the width of the major digit of G. yumenensis is more uniform 2014; Liu D et al., 2014). In IVPP V18958, the trochlea of (Fig. 3c). The minor digit of both IVPP V18958 and metatarsal II ends only slightly proximally to the trochleae of BMNHC-Ph1342 only retain the proximal wedge-shaped either metatarsal III or IV and the trochlea of metatarsal IV phalanx, which proximal end is slightly wide and its length is ends nearly at the same level as that of metatarsal III (Fig. 4a). more than half of the first phalanx of the major digit. In BMNHC-Ph1342, the trochlea of metatarsal II ends much The ischium of IVPP V18958 is about two thirds of the more proximally than the trochleae of either metatarsal III or length of the pubis, with a concave ventral margin and a IV and the trochlea of metatarsal IV ends more proximally sharply tapered distal half (Fig. 4a) (Zhou S et al., 2014). The than that of metatarsal III (Fig. 4b). However, the morphology ischium of BMNHC-Ph1342 is less than half the length of the of the distal part of the tarsometatarsus of both specimens pubis, with the distal one third curved ventrally (Liu D et al., show triangle pattern, which is an important feature of 2014). Based on the reobservation, the pubes of IVPP V18958 terrestrial birds (Zhang YG, 2006). These similar and are broken or overlapped by the tibiotarsus (Fig. 4a), and the different features are probably related to interspecific fragile part of the distal ischium of BMNHC-Ph1342 may be differences. absent (Fig. 4b). The pubis of IVPP V18958 are smoothly The pedal phalangeal formula is 2-3-4-5-x in IVPP recurved with a boot-shaped pubis symphysis distally. V18958 and BMNHC-Ph1342 (Zhou S et al., 2014; Liu D et However, the posterior one third of the pubis of BMNHC- al., 2014). However, there are some differences between Ph1342 is strongly recurved (Fig. 4b). them. In IVPP V18958, pedal digit IV is as robust as digit III The femur of BMNHC-Ph1342 is shorter than the and slightly shorter than digit III, and all ungual phalanges tarsometatarsus (femur/tarsometatarsus=0.96), consistent with bear a pronounced flexor process (Fig. 4a) (Zhou S et al., that of G. yumenensis (femur/tarsometatarsus=0.92), but 2014). In BMNHC-Ph1342, pedal digit IV is prominently opposite to that of IVPP V18958 (femur/tarsometatarsus= slender and slightly longer than digit III, and all ungual 1.13). Considering that the right femur is mostly covered by phalanges lack a pronounced flexor process (Fig. 4b). The the sternum and the left femur is somewhat crushed and pedal digit II-2 of IVPP V18958 is longer than digit II-1 broken in IVPP V18958, the reported femur length is (Zhou S et al., 2014). Actually, they are nearly the same probably distored. The medial condyle of the tibiotarsus is length as the condition in BMNHC-Ph1342. In G. wider than the lateral condyle both in IVPP V18958 and yumenensis, pedal digit IV is much longer than digit III (Fig. 4c),

(a) (b) (c)

mi al1 rra al mm al1 al al2 rhu mm mm mi1 mm2 mi mm1 al1 mm3 al2 mi mi1 rra rul mm1 mi1 rhu mm1 rra mm2 rul mm2 mm3 rul (d) mm co al1 mi mm3 al sc hu ul ra

1 cm 1 cm

Fig. 3. Photograph of the forelimbs of Iteravis huchzermeyeri IVPP V18958 (a), Gansus zheni BMNHC-Ph1342 (b) and Gansus yumenensis (c) (d). rhu –right humerus; hu –humerus; rul –right ulna; ul –ulna; rra –right radius; ra –radius; al –alular metacarpal; mm –major metacarpal; mi–minor metacarpal; al1/2–alular digit 1/2; mm1/3–major digit 1/3; mi1–minor digit 1; co–coracoid; sc–scapula. 202 Ju et al. / China Geology 2 (2021) 197−204 with a length ratio (1.20) greater than that of IVPP V18958 corresponding to the hooked anterolateral process of

(0.93) and BMNHC-Ph1342 (1.02). BMNHC-Ph1342. The development difference of the anterolateral process is therefore likely to be related to 4. Discussion ontogenetic stage. The proximal end of the carpometacarpus is not completely fused in IVPP V18958 (Zhou S et al., 2014). The proportions of forelimb to hindlimb lengths are 0.97 Actually, it was probably separated during the fossilization and 1.02 in IVPP V18958 and BMNHC-Ph1342, respectively. process as it partly lay on the ulna; the distal end is wholly Based on the elongated tibiotarsus, metatarsals and pedal fused. Liu D et al. (2014) described that both pubes formed a digits, they are both terrestrial wading birds (Zhou S et al., short pubic symphysis in BMNHC-Ph1342. The pubic 2014; Liu D et al., 2014; Fig. 5). The extensor process of the symphysis of BMNHC-Ph1342 is nearly one third of the alular metacarpal is used to attach the flying muscle. This pubic shaft length, which is the same as that in IVPP V18958 structure is present in IVPP V18958 but absent in BMNHC- and relatively longer than that of G. yumenensis. The posterior Ph1342. However, the developed sternum of BMNHC- part of the pubis is not strongly curved in IVPP V18958, Ph1342 indicates that it also has strong flight ability. The which may be resulted by the deformation judging by the split absence of the extensor process is probably due to near the pubic symphysis. The left and right ischium of preservation. The ventral surface of the synsacrum has a wide BMNHC-Ph1318 are preserved between the pubes and the groove in BMNHC-Ph1342 (Liu D et al., 2014), while it is caudal vertebrae. They are slightly different in morphology, smooth in IVPP V18958 (Zhou S et al., 2014). According to which indicates that they were deformed during the our reobservation, most of the synsacrum of IVPP V18958 is fossilization or preservation process. The extremely slender covered by other bones, with only the proximal and distal and tapered distal end of the ischium was probably not ends exposed. The coracoid has a hook-shaped anterolateral preserved in BMNHC-Ph1342. This part is too fragile to be process in BMNHC-Ph1342 (Liu D et al., 2014), while the well-preserved because it is also broken in IVPP V18958. lateral margin of the coracoid is reported as straight in IVPP Zhou S et al. (2014) described that the pedal digit II-1 of V18958 (Zhou S et al., 2014). Our observations reveal that IVPP V18958 was slightly shorter than pedal digit II-2. In the lateral margin of the left coracoid is not straight in IVPP fact, the proximal end of the left pedal digit II-1 was covered V18958, and it retains a slightly convex ridge at the position by the tarsometatarsus, while the right pedal digit II-1 was

(a) (b) (c) fem st fem

g pu fi g pu il g fem is syn fem fem ti is il ti pu ti ti ti pu

ti tmt tmt tmt tmt

I tmt I I tmt I

II I II II II III

II II IV III III IV IV IV IV III III IV III 1 cm

Fig. 4. Photograph of the hindlimbs and pelvic girdles of Iteravis huchzermeyeri IVPP V18958 (a), Gansus zheni BMNHC-Ph 1342 (b) and Gansus yumenensis (c). il –ilium; pu –pubis; is –ischium; fem –femur; ti –tibiotarsus; tmt –tarsometatarsus; I –pedal digit I; II –pedal digit II; III–pedal digit III; IV–pedal digit IV; st–sternum; syn–synsacrum; g–gastroliths. Ju et al. / China Geology 2 (2021) 197−204 203

Jiufotang Formation. Based on our field investigation and latest research results (Wu ZJ et al., 2018; Gao FL et al., 2018), the stratigraphic occurrence for both specimens should

be the Lower Cretaceous Jiufotang Formation.

5. Conclusion

Based on detailed comparisons of the anatomical characteristics, the authors conclude that Gansus zheni Liu D et al., 2014 is a junior synonym of Iteravis huchzermeyeri Zhou S et al., 2014. Iteravis huchzermeyeri has nomenclatural priority because it was published 15 days before Gansus zheni. Through the reobservation and comprehensive study of the type and referred specimens, the authors revised the diagnosis of Iteravis huchzermeyeri. Based on our field investigation and latest research results, the stratigraphic occurrence of Iteravis huchzermeyeri is revised as the Lower

Cretaceous Jiufotang Formation.

CRediT authorship contribution statement

Shu-bin Ju, Xu-ri Wang, Yi-chuan Liu and Yang Wang contributed to the design and implementation of the research, Fig. 5. Life scene of Iteravis huchzermeyeri (drawn by Chuang to the analysis of the results and to the writing of the Zhao). manuscript. completely exposed and it was nearly equal to pedal digit II-2, Declaration of competing interest which is the same as the condition in BMNHC-Ph1342.

The authors declare no conflicts of interest. Originally, BMNHC-Ph1342 was referred to the genus of Gansus because it is very similar with G. yumenensis (Liu D Acknowledgement et al., 2014). But there are some obvious differences to separate them in different genera. The interclavicular angle of The authors would like to thank Dr. Chiappe Luis, Dr. BMNHC-Ph1342 (about 60°) is significantly greater than that Shuang Zhou and Dr. Ya-ming Wang for providing high- of G. yumenensis (about 40°). The sternal margin of the resolution photos of the studied materials and constructive coracoid extends nearly equally laterally and medially in comments that improved this manuscript. The authors are BMNHC-Ph1342, while it extends much more laterally than really appreciating Dr. Trevor Worthy, Prof. Hai-lu You and medially in G. yumenensis. The rostral margin of the sternum Dr. Ya-ming Wang for their constructive comments. This of BMNHC-Ph1342 is strongly arched, forming an acute work was supported by projects from the National Natural angle slightly less than 90°, which is much lesser than the Science Foundation of China (41872018, 41672019) and the obtuse angle (about 140°) of G. yumenensis. The alular China Geological Survey (DD20190602) awarded to Xu-ri metacarpal of BMNHC-Ph1342 is short and narrow, slightly Wang. more than half the width of the major metacarpal, with a small extensor process. The alular metacarpal of G. yumenensis is References nearly half the width of the major metacarpal. The first phalanx of the major digit is much wider than the second one Chiappe LM. 2002. Basal Bird Phylogeny: Problems and Solutions. in BMNHC-Ph1342. The major digit of G. yumenensis is Mesozoic Birds Above the Heads of Dinosaurs, 1045–1082. Chiappe LM, Zhao B, O ’Connor JK, Gao CL, Wang XR, Habib M, slenderer with a slight thicker first phalanx. Pedal digits III Marugan-Lobon J, Meng QJ, Cheng XD. 2014. A new specimen of and IV of BMNHC-Ph1342 are nearly equal in length, while the Early Cretaceous bird Hongshanornis longicresta: Insights into pedal digit IV of G. yumenensis is much longer than pedal the aerodynamics and diet of a basal ornithuromorph. PeerJ 2, e234. digit III. Claws of pedal digits III and IV of BMNHC-Ph1342 doi: 10.7717/peerj.234. lack prominent pendant flexor tubercles, while they are Gao FL, Jiang Y, Pan YQ, Wang X, Wu ZJ, Fan S, Dai DY. 2018. present in G. yumenensis. Therefore, Iteravis huchzermeyeri Division and significance of the precious fossil-bearing beds of is genetically distinct from Gansus yumenensis. Jiufotang Formation in Sihedang area, Liaoning province. Geology and Resources, 27(6), 503–507 (in Chinese with English abstract). Both IVPP V18958 and BMNHC-Ph 1342 were doi: 10.3969/j.issn.1671-1947.2018.06.001. uncovered from Sihedang town near Lingyuan City, western Hou LH, Zhang J. 1993. A new fossil bird from Lower Cretaceous of Liaoning. But IVPP V18958 was reported from the Yixian Liaoning. Vertebrata PalAsiatica, 31(3), 217–224. Formation, while BMNHC-Ph1342 was reported from the Huang JD, Wang X, Hu YC, Liu J, Peteya J, Clarke JA. 2016. A new 204 Ju et al. / China Geology 2 (2021) 197−204

ornithurine from the Early Cretaceous of China sheds light on the English abstract). doi: 10.19657/j.geoscience.1000-8527.2018.003. evolution of early ecological and cranial diversity in birds. PeerJ, You HL, Lamanna MC, Harris JD, Chiappe LM, O’Connor JK, Ji SA, 4(1), e1765. doi: 10.7717/peerj.1765. Lü JC, Yuan CX, Li DQ, Zhang X, Lacovara KJ, Dodson P, Ji Q. Liu D, Chiappe LM, Zhang YG, Bell A, Meng QJ, Ji Q, Wang XR. 2006. A nearly modern amphibious bird from the Early Cretaceous 2014. An advanced, new long-legged bird from the Early Cretaceous of northwestern China. Science, 312(5780), 1640–1643. doi: of the Jehol Group (northeastern China): Insights into the temporal 10.1126/science.1126377. divergence of modern Birds. Zootaxa, 3884(3), 253–266. doi: Zhang YG. 2006. The morpholigy of the distal tarsometatarsus in 10.11646/zootaxa.3884.3.4. perching and terrestrial birds. Sichuan Zool, 25(1), 27–32 (in O ’Connor JK, Gao KQ, Chiappe LM. 2010. A new ornithuromorph Chinese with English abstract). doi: 10.3969/j.issn.1000-7083.2006. (Aves: Ornithothoraces) bird from the Jehol Group indicative of 01.005. higher-level diversity. Journal of Vertebrate Paleontology, 30(2), Zheng XT, O ’Connor JK, Wang XL, Wang Y, Zhou ZH. 2018. 311–321. doi: 10.1080/02724631003617498. Reinterpretation of a previously described Jehol bird clarifies early Wang M, Zheng XT, O ’Connor JK, Lloyd GT, Wang XL, Wang Y, trophic evolution in the Ornithuromorpha. Proceedings of the Royal Zhang XM, Zhou ZH. 2015. The oldest record of ornithuromorpha Society, Biological Sciences, 285(1871), 20172494. doi: 10.1098/ from the early cretaceous of China. Nature Communication, 6, 6987. rspb.2017.2494. doi: 10.1038/ncomms7987. Zhou S, O ’Connor JK, Wang M. 2014. A new species from an Wang M, Zhou ZH, Zhou S. 2016. A new basal ornithuromorph bird ornithuromorph (Aves: Ornithothoraces) dominated locality of the (Aves: Ornithothoraces) from the Early Cretaceous of China with Jehol Biota. Chinese science bulletin, 59(36), 5366–5378. doi: implication for morphology of early Ornithuromorpha. Zoological 10.1007/s11434-014-0669-8. Journal of the Linnean Society, 176(1), 207–223. doi: 10.1111/ Zhou ZH, Zhang FC. 2001. Two new ornithurine birds from the Early zoj.12302. Wang X, Huang JD, Hu YC, Liu XY, Peteya J, Clarke JA. 2018. The Cretaceous of western Liaoning, China. Chinese Science Bulletin, earliest evidence for a supraorbital salt gland in dinosaurs in new 46, 1–7. doi: 10.1007/BF03184320. Early Cretaceous ornithurines. Scientific Reports, 8(1), 3969. doi: Zhou ZH, Zhang FC. 2005. Discovery of an ornithurine bird and its 10.1038/s41598-018-22412-8. implication for Early Cretaceous avian radiation. Proceedings of the Wang XR, Cau A, Kundrát M, Chiappe LM, Ji Q, Wang Y, Li T, Wu National Academy of Sciences of the United States of America, 102, WH. 2020. A new advanced ornithuromorph bird from Inner 18998–19002. doi: 10.1073/pnas.0507106102. Mongolia documents the northernmost geographic distribution of the Zhou ZH, Zhang FC. 2006. A beaked basal ornithurine bird (Aves, Jehol paleornithofauna in China. Historical Biology, 1–13. doi: Ornithurae) from the Lower Cretaceous of China. Zoologica Scripta, 10.1080/08912963.2020.1731805. 35, 363–373. doi: 10.1111/j.1463-6409.2006.00234.x. Wu ZJ, Gao FL, Pan YQ, Wang X. 2018. Division and correlation of the Zhou ZH, Zhang FC, Li ZH. 2009. A new basal ornithurine bird Jiufotang Formation and their rare fossil-bearing beds in western (Jianchangornis microdonta gen. et sp. nov.) from the lower Liaoning, China. Geoscience, 32(4), 758–765 (in Chinese with Cretaceous of China. Vertebrata PalAsiatica, 47, 299–310.